Micro gas turbine engines are well-known in the art and have found particular utility in powering projectiles such as a missile. In this application, the turbine engine is operated in a substantially constant environment and for a relatively limited duration. In addition, the turbine engine is typically cycled once (i.e. started once and stopped once) and operated at a near maximum output generation. As such the operating conditions are substantially constant and well defined. Furthermore, the internal components of the gas turbine engine, such as the bearings, are not subjected to repeated cycling through a range of operating speeds.
However, to date, micro gas turbine engines have not proven useful in applications where the engine is required to operate in a variety of environments over a prolonged period of time at less than maximum output generation. A primary difficulty has been the inability to properly cool and lubricate the bearing assemblies. Thus, micro gas turbine engines have not been used in applications which require repeated cycling and/or operation in many different environments such as co-generation.
Instead co-generators have been developed which use separate heat generating and power generating sources. For example, gas heaters or furnaces typically use a fuel which is delivered to a burn chamber where the fuel is ignited and a blower unit powered by an external power source which blows the heated air generated in the combustion chamber out of the heater. Accordingly, systems of this type do not take advantage of the heat by-product generated during power generation.
The present invention provides a self-sustaining system wherein a gas turbine engine functions as a power head for a co-generator to generate heat and rotary drive power for driving the fan of the heat exchanger, as well as the auxiliary components of the engine such as an electrical generator for charging a battery which operates the other components of the system. The overall concept of the present invention is to provide a co-generator which utilizes a micro gas turbine engine for both energy generating functions.
A primary object of the present invention is to provide a co-generator which is substantially smaller, and thus portable, than current systems for a given heat generating capacity.
A further object of the present invention is to provide a gas turbine engine as a power head for the generation of heat, thereby eliminating direct impingement of combustion on a heat exchanger element, and significantly increasing the durability and life span of the heater unit.
Another object of the present invention is to provide a quick-starting, self-sustaining co-generator which is rugged in design and has the ability to operate in adverse locations (e.g. on temporary platforms) and in adverse conditions (e.g. sub-zero temperatures).
An additional object of the present invention is to provide a self-contained co-generator in which at least a portion of the gas turbine engine is coaxially located with and surrounded by an annular heat exchanger such that the gas turbine engine is protected and muffled.
A further object of the present invention is to provide an extremely high efficiency co-generator which converts a high percentage of the energy of the fuel.
Still a further object of the present invention is to provide a bearing assembly for a gas turbine engine which is effectively cooled and lubricated by the combustion fuel such that the gas turbine engine can be repeatedly started and stopped, as well as operated at various power outputs without damage to the bearing assembly.
In a preferred embodiment, the present invention generally includes a gas turbine engine having a combustor which is coaxially arranged with the compressor and turbine such that the micro turbo heater housing surrounds the gas turbine engine. The turbo heater further includes a heat exchanger assembly which may take the form of a simple housing, an air-to-air heat exchanger, an air-to-liquid heat exchanger, a catalytic converter, or any combination thereof. In this manner, the turbo heater can be used to generate a heated air supply, a heated water supply or both a heated water supply and a heated air supply. Furthermore, the carbon monoxide content of the heated air can be controlled depending on the particular application.
Further scope of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.